Field of the Invention
The present invention relates to a conveying device configured to convey a developer, and more particularly, to a process cartridge and an image forming apparatus having such a conveying device.
The term “process cartridge” corresponds to a member including at least an image bearing member. For example, a process cartridge having an electrophotographic image forming system includes an electrophotographic photosensitive drum, which corresponds to the image bearing member, and a process device, which acts on the electrophotographic photosensitive drum. The electrophotographic photosensitive drum and the process device are integrated into a cartridge. The process cartridge described above is configured to be detachably attached to a main body of an electrophotographic image forming apparatus. Examples of the process device include a cartridge having at least one of a developing device, a charging device, and a cleaning device integrated therein.
The electrophotographic image forming apparatus is configured to form an image on a recording material by using the electrophotographic image forming system.
Examples of the electrophotographic image forming apparatus include, for example, electrophotographic copying machines, electrophotographic printers (LED printers, laser beam printers) facsimile machines, and word processors.
Description of the Related Art
An electrophotographic image forming apparatus (hereinafter, also referred to simply as “image forming apparatus”) is configured to form an image by uniformly charging a drum-shaped photosensitive member, which corresponds to an image bearing member, selectively exposing the charged photosensitive drum to form an electrostatic latent image (an electrostatic image) on the photosensitive drum, developing the electrostatic latent image formed on the photosensitive drum as a developer image (a toner image) by using toner, which corresponds to a developer, transferring the toner image formed on the photosensitive drum to a recording material such as a recording sheet and a plastic sheet, and fixing the toner image transferred to the recording material to the recording material by application of heat and pressure, thereby completing image recording.
The image forming apparatus as described above generally requires supplementation of toner and maintenance of various process devices. In order to facilitate supplementation of toner and maintenance, a configuration of a process cartridge including the photosensitive drum, a charging device, and a developing device housed together in a form of a process cartridge, which is detachably attachable with respect to an main body of the image forming apparatus, has already been put to practical use.
According to the process cartridge system described above, since a user can perform maintenance of the apparatus on his/her own, operability is significantly improved. Therefore, an image forming apparatus having superior usability is provided. Therefore, the process cartridge system described above is widely employed in the field of the image forming apparatus.
Some of the process cartridges as described above may need to convey toner to a position at a distance (Japanese Patent Laid-Open No. 2006-133465, Japanese Patent No. 3851530). Japanese Patent Laid-Open No. 2006-133465 discloses a configuration in which two screws are arranged in an overlapped manner to convey the toner to a position at a distance to accommodate a requirement of the toner conveyance. Two such screws arranged in the overlapped manner allow drive transmission and toner delivery to be performed simultaneously.
However, in the configuration having the screws arranged in the overlapped manner as described in Japanese Patent Laid-Open No. 2006-133465, the thickness (height) of a portion of a container that accommodates the screws in an overlapped manner needs to be at least double the thickness (height) of one screw. Therefore, a conveying device configured to convey the developer is increased in the size, and the image forming apparatus may also be increased in the size correspondingly.